1. Field of the Invention
The invention pertains to the field of biomaterial structures and, more particularly, to systems and methods that control the mechanical and biological properties of a biomaterial structure by controlling how the biomaterial is deposited to form the biomaterial structure.
2. Description of Related Art
The demand for tubular constructs for tissue engineering is high given the interest in microvascular grafts, nerve guides, and pre-vascularized tissues. Microvascular grafts are described, for example, by Baguneid, M. S. et al. Tissue engineering of blood vessels. Br J Surg (2006), 93:282-290; Kannan, R. Y. et al. Polyhedral oligomeric silsequioxane-polyurethane nanocomposite microvessels for an artificial capillary bed. Biomaterials (2006), 27:4618-4626; and Lovett, M. et al. Silk fibroin microtubes for blood vessel engineering. Biomaterials (2007), 28:5271-5279, the contents of these publications being incorporated herein by reference. Nerve guides are described, for example, by Yang, Y. et al. Development and evaluation of silk fibroin-based nerve grafts used for peripheral nerve regeneration. Biomaterials (2007), 28:5526, the contents of which are incorporated herein by reference. Pre-vascularized tissues are described, for example, by Jain, R. K. et al. Engineering vascularized tissue. Nat Biotechnol (2005), 23:821-823; and Fidkowski, C. et al. Endothelialized microvasculature based on a biodegradable elastomer. Tissue Eng (2005), 11:302-309, the contents of these publications being incorporated herein by reference.
In order to form vessels with desired properties for a given application, a system is required that can functionally control parameters and processing techniques to reproducibly manufacture tubes with relevant properties. To date, vessels have been commonly made using biodegradable scaffolds and tubular molds, methods where the scaffold deposition is accomplished without control of polymer or fiber alignment, or by electrospinning, which requires optimization of several processing steps (e.g., mandrel selection, voltage, and humidity). The use of biodegradable scaffolds is described, for example, by Niklason, L. E. et al. Morphologic and mechanical characteristics of engineered bovine arteries. J Vasc Surg (2001), 33:628-638; and Remuzzi, A. et al. Vascular smooth muscle cells on hyaluronic acid: culture and mechanical characterization of an engineered vascular construct. Tissue Eng (2004), 10:699-710, the contents of these publications being incorporated herein by reference. The use of tubular molds is described, for example, by Isenberg, B. C. et al. Endothelialization and flow conditioning of fibrin-based media-equivalents. Ann Biomed Eng (2006), 34:971-985, the contents of which are incorporated herein by reference. The use of electrospinning is described, for example, by Soffer, L. et al. Silk-based electrospun tubular scaffolds for tissue-engineered vascular grafts. Journal of Biomaterials Science, Polymer Edition (2008), 19:653, the contents of which are incorporated herein by reference.